Lithium-ion batteries are commonly used electrical energy sources for a variety of applications, such as electronic devices and electric vehicles. A lithium-ion battery typically includes a negative electrode (e.g., graphite) and a positive electrode (described below) that allow lithium ions and electrons to move to and from the electrodes during charging and discharging. An electrolyte solution in contact with the electrodes provides a conductive medium in which the ions can move. To prevent direct reaction between the electrodes, an ion-permeable separator is used to physically and electrically isolate the electrodes. When the battery is used as an energy source for a device, electrical contact is made to the electrodes, allowing electrons to flow through the device to provide electrical power, and lithium ions to move through the electrolyte from one electrode to the other electrode.
The positive electrode typically includes a conductive substrate supporting a mixture (e.g., applied as a paste) having at least an electroactive material, a binder, and a conductive additive. The electroactive material, such as a lithium transition metal oxide, is capable of receiving and releasing lithium ions. The binder, such as polyvinylidene fluoride, is used to provide mechanical integrity and stability to the electrode. Typically, since the electroactive material and the binder are electrically poorly conducting or insulating, the conductive additive (e.g., graphite and carbon black) is added to enhance the electrical conductivity of the electrode. The conductive additive and the binder, however, are generally not involved in electrochemical reactions that generate electrical energy, so these materials can negatively affect certain performance characteristics (e.g., capacity and energy density) of the battery since they effectively lower the amount of electroactive material that can be contained in the positive electrode.